Godfather: The Lost Years, Paperback/Mark Winegardner

Takes place in the years 1955-65, but it is built upon the story of that 'year of delicate political manoeuvring' - and how, in winning the battle of that year, Michael Corleone set the stage to lose the war. This novel traces the nexus of ambitious, audacious decisions that Michael Corleone implements, and their ultimate failure.